You speak pretty definitively on the topic. I'm guessing you have some experience with construction that's worth sharing? Would love to hear a positive story of how it turned out!
I spent a few years doing under the table construction and also picked up the skills to work on mechanical things around the same time. Then I went to college, got a career and spent some money picking up the skills required to work in metal. Electrical and plumbing (not just for water) are things you kind of have to pick up along the way. I'm no means a professional at any of these skills because I don't get 40hr of practice a week. Nor am I unique. A lot of successful people from blue collar backgrounds wind up with similar skills. Even though I have software money now I couldn't afford to pay people to build the things I can build myself.
I became a homeowner as a never-interested DIY with EE/CS degrees. We had an unfinished basement that we paid the builder to finish only the electrical, plumbing, and framing. I'd always heard drywall'ing was easy so I left that for me to do.
At the time I knew nothing about lighting, fixtures, eletrical work, etc. Ended up agreeing to J-boxes for basement lights rather than cans, and a few other money-saving things (for the electrician).
Before doing the drywall myself, I ended up rerunning all the basement lights, running tons of outlets, installed an electrical subpanel in my garage, new plumbing lines, etc. All inspected and approved on my own permits.
I maybe watched ~200 hours on youtube (easy to do at 2x speed) and read a lot of electrical and plumbing code. But when I was done it was "done right" and not done to "save money".
I ended up saving a ton of money on the electrical and plumbing, easily in the thousands, and only saved $700 on the drywall labor. Moral of the story, don't hang your own drywall by yourself. Pay for it if you can't get a couple friends to help.
Electrical and plumbing are relatively easy compared to anything that requires accurate measuring and cutting.
The latter can really kill a project if you can't get it right consistently, preferably first time.
That's where the skill comes in - not just the physical labour, but the experience needed to make allowances for material tolerances and other possible gotchas.
Professionals (should) have that knack, amateurs rarely will.
Generally all contractors say "the next guys will take care of that". For example, when framing you don't really care if the studs are really straight or if the walls are square. The "next guy" will take care of that.
True enough, when I was drywalling I had the builder come back to take care of some bowed studs that should never have been used.
I've also volunteered at Habitat for Humanity and can confirm that very little "accurate measuring and cutting" was occurring. They'd quickly measure some things, shout out numbers, and then use a circular saw to rough cut it out. But that was it - they didn't refine it after that and went about their merry way.
I have to believe that the accuracy of a foundation is more important but I think it's a fool's dream. They get "close" and they're checked out before the "next guy" has to fix it.
Maybe I am just bad at it but I can't get anything done DIY to fit properly. It's always off by like 1-2mm which means holes don't align, there's a gap in the baseboard, etc. I have to throw the entire part away and then pay someone to do it properly.
Unless a 3d printer or CNC machine is responsible for the accuracy you better count me out.
Ah, I did pay someone to do the millwork and trim work. You need a very accurate miter saw and a lot of experience to make perfect niters. I’m getting there but I still get off by a 1/16tb” to a 1/32nd” often.
The finish work is the final last guy. The guy that did our trim would randomly yell out swear words every 20 minutes. His life is hard. And he was expensive.
A couple of jobs a contractor I used for a long time (before he, sadly, retired) involved some drywall. He got drywall specialists to do it. He said they were far faster and cheaper than him doing it himself.
I do have a guest bedroom in my house where I once had some time during a holiday shutdown when my job situation was a bit perilous. I had some crumbling plaster so I put some drywall up. It's... functional.
Painting is one thing I do myself. I do it enough I got reasonably good at it and--for touchup--I can reasonably take shortcuts that someone I was paying couldn't.
